Heating problem

[brian93]

Hi, i recently fitted a new thermostat on my 2002 vtr, since doing this the fan has been cutting in very regular, my heaters are hit and miss sometimes blowing hot air sometimes wont blow hot, the temprature gauge will go over the middle mark but then drop again within seconds then back up n down, engine management light came on yesterday for about 30 mins then went off and aint came on again since, can anyone give me an idea on this? Thanks!

[marrygold]

bleed it

[axsaxoman]

remove rad cap --stuff a 2 litre coke bottle in with a rag , with bottom cut off
fill half way up --open bleeders =close again when water present and run for few mins and stop +then run again --if its air locked that will fill it up

your rad is lower than engine and heater so just opening bleeders won,t do it
needs to have head of water higher than it to get all air out
usually you hear grurggling noise from heater if it has air in it
,could also be heater matrix is partially blocked
it is 15 years old !!
but bleed correctly first

[brian93]

fitted a new thermostat sensor which seems to have sorted the overheating problem, the past few days the water has dropped so had to top it up i believe this is as air is working its way out the system? i know its certainly not just using water. as for the heaters though, it seems when i first turn them on they are luke warm or nice and hot, but within 20 seconds of them been on they begin to blow cold. thanks for the reply

[AdamH]

search for the bleed guide I have on here...

If you hear a trickling water noise on startup from old you have trapped air.

The lower hose is higher then the fill point so air will always be trapped unless you bleed it correctly using the correct Citroen bleeding tool which screws onto the fill point... Others use a bottle but its not perfect but could work if you make a air tight seal.